John Taintor Foote helped adapt his novel in this romance of feuding horse-breeders that won an Oscar for Walter Brennan's crotchety performance.
In April 1861 horse-breeders John Dillon (Douglass Dumbrille) and Thad Goodwin (Russell Hicks) take opposite sides over secession. Dillon's Union troops confiscate Goddwin's horses except for the foals. Goodwin aims a pistol, and Dillon shoots him dead. Little Peter Goodwin (Bobs Watson) cries and feeds the foals.
In 1938 old Peter Goodwin (Walter Brennan) runs the thoroughbred farm. Jack Dillon (Richard Greene) returns after eight years and wants to breed horses; but his father John Dillon (Moroni Olsen) persuades him to work in his bank. John Dillon fires black Ben (George Reed) for stealing, and Jack gives him money. Peter wants more stables, but Thad Goodwin (Charles Waldron) invests in cotton. Peter tells Sally Goodwin (Loretta Young) to stay away from Jack Dillon. Ben says the Dillons turned him out after fifty years, and Peter hires him. Goodwin asks Dillon for a loan and wins any colt he wants on a dice throw. Jack shows Sally his horse. Dillon persuades the bank board to deny the loan to Goodwin over Jack's objection. When cotton goes down, Goodwin collapses and dies. Jack blames his father.
Peter watches the auction of his horses. Jack tells Ben not to say who he is. Jack tells Sally he left the Dillons and will train her horse for free. In a storm Sally's car is blocked by a falling tree, and she rides her horse to get medicine for her mother over Peter's objection. Sally says good-bye to the servants. Jack gives Ben money to keep quiet and learns that Sally's horse had his legs injured on the paved road. Sally shows Jack the note for John Dillon's colt. Peter and Sally go to John Dillon, who agrees to give up a colt. Bob Slocum (Willard Robertson) hides the best two colts. Peter finds Postman but persuades Sally to take a smaller black one. Jack names him Bluegrass and trains him. Sally asks Jack to take her to a dance at Lucy's. He says no but kisses her.
Jack tells Sally that Bluegrass ran a mile in 1:37. Peter bets $100 at 20-1, and Bluegrass wins. Sally learns that Jack is a Dillon, and Jack learns he was fired. Jack finds Sally at a dance and tries to explain. Sally has a doctor examine Peter, who insists he is going to the derby. Sally follows Jack's advice not to use the whip on Bluegrass. Jack learns that Slocum hid the colts and apologizes to his father. Peter and Sally see Jack and his father shake hands. In the race the whip causes Bluegrass to fall back; but after that is stopped, Bluegrass wins. In the final scene John Dillon speaks the eulogy at Peter's funeral.
Stereotyped portrayal of blacks on the farm indicates this film could have been set in the 19th century. Young love overcomes traditional hatreds.